Vacuum cleaners operated by suction for cleaning the surface at the bottom of a swimming pool have long been known. Some of the prior art pool cleaners include stationary brushes and at least one of them includes rotary brushes, but which are only gently engageable with the surface at the bottom of the pool for dislodging particulate material from the pool floor and for contributing to localized turbulence.
See for example, the following prior art:
______________________________________ U.S. Pat. ISSUE No. DATE INVENTOR TITLE ______________________________________ 4,094,031 June 13, 1978 Cellini CLEANING APPA- RATUS FOR SE- LECTED SMALL AREAS OF A SWIMMING POOL 4,193,228 Mar 18, 1980 Bowler WATER DRIVEN TOOL 4,463,525 Aug 7, 1984 Sheber HAND-HELD CLEANING TOOL WITH REMOTE WATER TURBINE POWER SOURCE 4,692,956 Sept 15, 1987 Kassis POOL VACUUM 4,734,954 Apr 5, 1988 Greskovics POOL SCRUBBER DEVICE 4,786,334 Nov 22, 1988 Nystrom METHOD OF CLEANING THE BOTTOM OF A POOL ______________________________________
The bristles at the bottom of the hand operated vacuum apparatus of Cellini are stationary.
Bowler and Greskovics each show a rotary cleaning tool for swimming pools that is operated by external water pressure.
Sheber discloses a rotary cleaning tool powered by a remote turbine, through which water is drawn by suction, for cleaning calcium from decorative tile above the surface of the water around the sides of the pool.
Kassis shows fixed stiff bristles arranged around a plurality of fine bristles. The fixed stiff bristles normally rest on the pool bottom. The fine bristles are normally spaced above the surface of the pool bottom and rotate to create turbulence with helically twisted blades which rotate as water is drawn past them by suction. The fine bristles readily flex when even light contact is made with the surface of the pool, rather than produce increased friction for effective cleaning of the pool bottom.
Nystrom shows a self propelled pool cleaner with rotary brushes rotated on a horizontal axis by an electric motor.